Although useful advances are being made in energy saving devices such as organic-based organic light emitting diodes (OLEDs), polymer light emitting diodes (PLEDs), phosphorescent organic light emitting diodes (PHOLEDs), and organic photovoltaic devices (OPVs), further improvements are still needed in providing better processing and performance. For example, one promising type of material is the conjugated, conducting polymer including, for example, polythiophenes. However, problems can arise with doping, purity, solubility, and processing, particularly when complex architectures need to be fabricated by solution processing. In particular, it is important for solution processing to have very good control over the solubility of alternating layers of polymer (e.g., orthogonal or alternating solubility properties among adjacent layers).
In particular, for example, hole injection layers and hole transport layers can present difficult problems in view of competing demands and the need for very thin, but high quality, films.
A need exists for a good platform system to control properties of hole injection and transport layers such as solubility, thermal stability, and electronic energy levels such as HOMO and LUMO, so that the materials can be adapted for different applications and to function with different materials such as light emitting layers, photoactive layers, and electrodes. In particular, good solubility and intractability properties are important. The ability to formulate the system for a particular application and provide the required balance of properties is also important. Interfacial effects are important.
A need also exists to find simpler and less expensive methods to fabricate electronic devices including OLEDs.